Direct And Indirect Human Contributions To Terrestrial Carbon Fluxes

Human-induced climate change is an important environmental issue worldwide, as scientific studies increasingly demonstrate that human activities are changing the Earth's climate. Even if dramatic reductions in emissions were made today, some human-induced changes are likely to persist beyond the 21st century. The Kyoto Protocol calls for emissions reporting that separates out management-induced changes in greenhouse gases from those changes caused by indirect human effects (e.g., carbon dioxide fertilization, nitrogen deposition, or precipitation changes), natural effects, and past practices on forested agricultural lands. This book summarizes a September 2003 workshop where leaders from academia, government and industry came together to discuss the current state of scientific understanding on quantifying direct human-induced change in terrestrial carbon stocks and related changes in greenhouse gas emissions and distinguishing these changes from those caused by indirect and natural effects.

Towards the Balance and Management of the Carbon Budget of the Biosphere The current state of misunderstanding of the global C cycle and our failure to resolve an issue that has been debated for 100 years (Jones and Henderson-Sellers, 1990) speaks loudly about the limitations of modem science when faced with the complexity of the biosphere. Efforts to understand and balance the global C budget have gone through several phases. First was a holistic view of the C budget as part of efforts to understand the geochemistry of the Earth (e. g. , Clarke, 1908). Next, came a period of data collection and sythesis which focused on the diversity of sectors of the biosphere. This phase culminated in the early 1970's with the realization that humans were greatly impacting the global C cycle as measured at the Mauna Loa Observatory (Keeling et al. , 1973). New syntheses of the global C budget emerged at this time (Woodwell and Pacan, 1973; Bolin et al. , 1979). The next phase was one of controversy and intense focus on particular sectors of the biosphere. The controversy rested on discrepancies about the role of the terrestrial biota in the global C cycle and the failure to account for sufficient C sinks to absorb all the C emitted by land-use change in the tropics (Woodwell et al. , 1978, 1983; Houghton et al. , 1983).

The term 'terrestrial carbon' refers to carbon contained in vegetation or soil stocks. The global carbon cycle plays an important role in sustaining agricultural productivity, biodiversity and forest ecosystems processes. This report presents the results of a workshop, held in Canada in February 2000 and organised by the Global Terrestrial Observing System (GTOS) in collaboration with the International Geosphere-Biosphere Programme (IGBP). The workshop was designed to review existing data and observation requirements regarding terrestrial carbon, identify major gaps and propose solutions.

While a number of gases are implicated in global warming, carbon dioxide is the most important contributor, and in one sense the entire phenomena can be seen as a human-induced perturbation of the carbon cycle. The Global Carbon Cycle offers a scientific assessment of the state of current knowledge of the carbon cycle by the world's leading scientists sponsored by SCOPE and the Global Carbon Project, and other international partners. It gives an introductory over-view of the carbon cycle, with multidisciplinary contributions covering biological, physical, and social science aspects. Included are 29 chapters covering topics including: an assessment of carbon-climate-human interactions; a portfolio of carbon management options; spatial and temporal distribution of sources and sinks of carbon dioxide; socio-economic driving forces of emissions scenarios. Throughout, contributors emphasize that all parts of the carbon cycle are interrelated, and only by developing a framework that considers the full set of feedbacks will we be able to achieve a thorough understanding and develop effective management strategies. The Global Carbon Cycle edited by Christopher B. Field and Michael R. Raupach is part of the Rapid Assessment Publication series produced by the Scientific Committee on Problems of the Environment (SCOPE), in an effort to quickly disseminate the collective knowledge of the world's leading experts on topics of pressing environmental concern.

Increased agricultural productivity is a major stepping stone on the path out of poverty in sub-Saharan Africa and South Asia, but farmers there face tremendous challenges improving production. Poor soil, inefficient water use, and a lack of access to plant breeding resources, nutritious animal feed, high quality seed, and fuel and electricity-combined with some of the most extreme environmental conditions on Earth-have made yields in crop and animal production far lower in these regions than world averages. Emerging Technologies to Benefit Farmers in Sub-Saharan Africa and South Asia identifies sixty emerging technologies with the potential to significantly improve agricultural productivity in sub-Saharan Africa and South Asia. Eighteen technologies are recommended for immediate development or further exploration. Scientists from all backgrounds have an opportunity to become involved in bringing these and other technologies to fruition. The opportunities suggested in this book offer new approaches that can synergize with each other and with many other activities to transform agriculture in sub-Saharan Africa and South Asia.

The glassy-winged sharpshooter is one of the more recent invasive pests to afflict California agriculture. The insect transmits a bacterial pathogen that causes Pierce's disease, which has impaired production of wine, table, and raisin grapes in California. The report recommends strengthening the process and the priorities for research funded by state agencies and wine industry groups to address Pierce's disease and its vector. Research should be focused on identifying feasible options for controlling the spread of the disease and providing sustainable approaches that are adaptable and affordable over the long term. Several avenues of research be pursued more intensely including the genetic makeup of the pathogen that triggers Pierce's disease, understanding the mechanisms that make grapes resistant to the disease, the possibilities of introducing predator enemies to the sharpshooter, and new ways to manage the planting of crops to help avoid spread of the disease.

The U.S. sheep industry is complex, multifaceted, and rooted in history and tradition. The dominant feature of sheep production in the United States, and, thus, the focus of much producer and policy concern, has been the steady decline in sheep and lamb inventories since the mid-1940s. Although often described as "an industry in decline," this report concludes that a better description of the current U.S. sheep industry is "an industry in transition."